The goal of this project is to collect the safety and effectiveness clinical data necessary to commercialize the SMARTPATCH(R) system for post-stroke shoulder pain (PSSP). The prevalence of stroke is approximately 8 million in the US, with 795,000 additional persons surviving a stroke each year. Moderate to severe shoulder pain develops in a quarter to a third of stroke survivors, amounting to a current population of over 2 million. Existing interventions have limited effectiveness, limited duration of benefit, and/or significant burden. Our team developed percutaneous peripheral nerve stimulation (PNS) delivered via our innovative Smartpatch system for the treatment of PSSP, which addresses the limitations of existing interventions. Of 60 subjects who received temporary percutaneous PNS therapy across multiple studies, 75% experienced clinically significant pain relief during stimulation, with a third becoming completely pain free. The majority of subjects reported sustained pain relief for at least 12 weeks after stimulation was turned off and many had sustained relief beyond one year. The objective of this project is to execute a prospective, randomized, double-blinded, placebo-controlled multicenter pivotal trial in support of US FDA regulatory clearance. Subjects will be randomized to either a treatment group, in which percutaneous PNS is delivered for 4 weeks; or a control (placebo) group, in which the percutaneous lead is placed in the same location and the subject is asked to use the system for 4 weeks but no stimulation is delivered. The specific aims of this project are to: 1) Demonstrate the clinical effectiveness of the Smartpatch system in reducing post-stroke shoulder pain; 2) Demonstrate the clinical effectiveness of the Smartpatch system in improving quality of life; and 3) Demonstrate the carry-over effect of the Smartpatch system at 12-weeks post-treatment. Upon successful completion of the pivotal trial, we will submit a 510(k) application to the FDA to obtain US market clearance for the Smartpatch system. Commercialization of the Smartpatch system will change how pain is managed by providing a drug-free, short-term, minimally-invasive, simple, reversible, safe, and effective treatment option, resulting in long-term pain relief and an improvement in the QOL of millions of US stroke survivors suffering from moderate to severe shoulder pain.